This invention relates to a photocontroller diagnostic system which, inter alia, detects whether the photocell and the relay of the photocontroller are faulty and which also provides an indication of a faulty relay or photocell condition by transmitting information about that condition to a remote base station and/or illuminating a signal light on the photocontroller.
Photocontrollers are typically mounted on street lights and operate to turn the light off during the day and on at night. Since the cost of servicing a single street light can cost $100 or more on busy roads and in busy areas, and since there are 60,000,000 street lights in the United States alone, the problem of servicing faulty photocontrollers is severe. For example, when the relay of the photocontroller fails, or when the photocell fails, the street light will remain on during periods of daylight thereby wasting electricity. Alternatively, a faulty relay or a faulty photocell could cause the lamp to remain off during the night causing a safety hazard. Since repair typically occurs during daylight hours, it is often difficult to detect the latter condition.
The problem of high pressure sodium (HPS) street lights cycling at the end of their useful life is also severe. The phenomena of cycling of HPS lamps as they age from use is caused by some of the electrode material being plated off the electrodes and then being deposited on the inside of the arc tube. This makes the tube darken and traps more heat inside the arc tube. As a result, an increased voltage is required to keep the lamp ignited or ionized. When the voltage limit of the ballast is reached, the lamp extinguishes by ceasing to ionize. Then, the lamp must cool down for several minutes before an attempt at re-ignition can be made. The result is xe2x80x9ccyclingxe2x80x9d wherein the worn out lamp keeps trying to stay lighted. The voltage limit is reached, the lamp extinguishes, and then after an approximately one-two minute cool down period, the arc tube re-ignites and the light output increases again and until the voltage limit is reached whereupon the lamp again extinguishes.
Cycling may waste electricity, cause RFI (radio frequency interference) which adversely effects communication circuits, radios, and televisions in the area, and may adversely effect and prematurely wear out the ballast, starter, and photocontroller.
For example, if an HPS lamp undergoes cycling for a many nights before it is finally serviced and replaced, the ballast or starter can be damaged or degraded. But, when the HPS lamp is replaced, this damage or degradation might not be detected. Later service calls then must be made to service these problems. The ballast and starter components are more expensive than the lamp or the photocontroller.
The cycling problem is well documented but so far the only solutions offered are to replace the HPS lamps with less efficient mercury lamps or to reconfigure existing photocontrollers with a special fiber optic sensor which senses light from the lamp and sends a signal to a microprocessor to indicate whether the lamp is on or off. After three on/off cycles, the microprocessor turns the lamp off and turns on a red strobe light which can be seen from the street. Unfortunately, this prior art solution requires modifications to the existing light fixture (e.g. a hole must be drilled in the fixture housing) and the use of an expensive fiber optic sensor. See, e.g., U.S. Pat. No. 5,235,252.
Another problem with all luminaries including HPS or other types of lamps is the cost involved in correcting the cycling problem and other faults such as a lamp out condition. For example, a resident may report a lamp out or a cycling condition but when the repair personnel arrives several hours later, the lamp may have cycled back on. Considering the fact that the lamp pole may be 25-35 ft. high, repair personnel can waste a considerable amount of time checking each lamp in the area. Also, repair and maintenance personnel may not be able to service a given residential area until daylight hours when all of the street lights are off by design.
It is therefore an object of this invention to provide a photocontroller diagnostic system and method.
It is a further object of this invention to provide such a photocontroller diagnostic system which detects and reports a faulty photocell and/or relay of the photocontroller to aid repair personnel in repairing failed photocontrollers.
It is a further object of this invention to provide such a photocontroller diagnostic system which conveniently resides on a microprocessor which itself is a component of the photocontroller.
It is a further object of this invention to provide a luminaire diagnostic system which, inter alia, detects and reports cycling street lights.
It is a further object of this invention to provide a method of monitoring luminaries such as street lights.
It is a further object of this invention to provide such a system and method which, because of its ability to detect cycling, saves electricity, reduces RFI, and prevents the premature failure of ballasts and starters associated with luminaries.
It is a further object of this invention to provide such a system and method which significantly reduces the cost of servicing and repairing luminaries such as street lights.
It is a further object of this invention to provide such a system and method which can be implemented in a cost effective way without the need for making complicated modifications to existing luminaries and/or the use of expensive fiber optic sensors.
It is a further object of this invention to provide such a system and such a method which provides a positive indication of a cycling or lamp off condition in real time.
It is a further object of this invention to provide a combined photocontroller and luminaire diagnostic system which is a part of the photocontroller and which detects a failed photocontroller relay, a failed photocontroller photocell, a failed lamp, and a cycling lamp condition.
This invention results from the realization that the proper operation of a photocontroller for a street lamp or other luminaire can be diagnosed by a microprocessor resident on the photocontroller and programmed to detect a faulty relay by reading whether current is drawn by the lamp during daylight hours and also programmed to detect a faulty photocell by determining whether the lamp remains continuously on or off for a present period of time such as twenty four hours.
This invention results from the further realization that cycling of a street light and other faulty luminaire conditions such as a lamp out condition can be detected by monitoring the load drawn by the lamp at different times and then comparing the load differences to pre-determined thresholds, that such detection can be accomplished by an inexpensive transformer added to the photocontroller circuitry and coupled to a specially programmed microprocessor, and that a transmitter can be linked to the microprocessor to transmit lamp out, lamp cycling, and other fault conditions to a location remote from the street lamp to initiate repair/maintenance services in real time. Alternatively, the microprocessor can illuminate one or a series of LEDs resident on the photocontroller to provide repair personnel with a positive indication regarding the condition of the photocontroller and/or lamp even in the daylight hours when the lamp is purposefully turned off. Further, the controller can shut the lamp off after a predetermined number of cycles. This feature eliminates ballast and starter degradation.
This invention features a photocontroller diagnostic system comprising a photocontroller including a sensor for determining the presence of daylight, and relay means, responsive to the sensor, for de-energizing a lamp during periods of daylight. A diagnostic subsystem is responsive to the photocontroller and includes: means for verifying the operability of at least one of the relay means and the sensor, and means, responsive to the means for verifying, for transmitting a signal representative of the operability of the relay means or the sensor.
The relay means typically includes a switch which when activated energizes a relay to present a voltage to the lamp. The means for verifying may include programming steps operable on a microprocessor which detect whether current is being drawn by the lamp during daylight hours to detect a faulty relay. The means for transmitting then preferably includes additional programming steps which send a relay fault signal when current is being drawn during daylight hours.
Alternatively, or in addition, the means for verifying includes programming steps, operable on a microprocessor, which detect whether the lamp is on or off for a period of time greater than a preset threshold to detect a faulty sensor. The means for transmitting then includes additional programming steps which send a sensor fault signal when the lamp is on or off for a period of time greater than the preset threshold (e.g., twenty four hours).
The diagnostic subsystem preferably includes a microprocessor which is a component of and integral with the photocontroller and programmed to detect a faulty relay and/or a faulty sensor (e.g., a photocell).
Further included are indicator means, responsive to the signal representative of the operability of the relay means or the sensor, for providing an indication of the operability of the relay means or the sensor means. Such as indicator means includes one or more visual alarms such as LED""s on the photocontroller. Alternatively, the indicator means may include a transmitter for transmitting the fault signals to a remote location.
The photocontroller diagnostic system of this invention may be combined with a luminaire diagnostic system which includes means for determining the operability of one or more components of the luminaire; and means, responsive to the means for determining, for transmitting a signal representative of the inoperability of the components of the luminaire, typically a failed lamp condition, and/or a cycling lamp condition. Such a combined luminaire and photocontroller diagnostic system comprises: a photocontroller circuit for automatically turning a lamp on during periods of darkness and off during periods of daylight; means for detecting a load drawn by the lamp; a microprocessor, responsive to the means for detecting, programmed to detect a condition of the lamp based on the load drawn by the lamp, and programmed to detect a condition of the photocontroller based on the load drawn by the lamp; and means, responsive to the microprocessor, for indicating the occurrence of a detected condition.
The programming which predicts a condition of the lamp based on the load drawn by the lamp and includes processing steps which reads the load shortly after the lamp is turned on then again after predetermined time, calculates the load difference, and determines whether the load difference exceeds a predetermined threshold to detect a failed lamp condition.
The programming which predicts a condition of the lamp based on the load drawn by the lamp may also include processing steps which calculates whether the load difference at predetermined times exceeds a predetermined threshold, and counts the number of times the load difference exceeds said predetermined threshold to detect a cycling lamp condition.
The programming which predicts a condition of the photocontroller based on the load drawn by lamp includes processing steps which detect whether current is drawn by the lamp during daylight hours to detect a relay fault condition.
The programming which predicts a condition of the photocontroller based on the load drawn by lamp may also include processing steps which detect whether the lamp is on or off for a period of time greater than a preset threshold to detect a photocell fault condition.
Usually, the load drawn by the lamp is used as the input to determine whether the lamp has failed or is cycling and also to determine whether the photocontroller relay and/or photocell components are faulty. Such a photocontroller diagnostic system comprises a photocontroller for automatically turning a lamp on during periods of darkness and off during periods of daylight; means for detecting a load drawn by the lamp; a microprocessor, responsive to the means for detecting, programmed to determine a condition of the photocontroller based on the load drawn by the lamp; and means, responsive to the microprocessor, for indicating the presence of a failed photocontroller. The microprocessor further includes programming which determines a condition of the lamp based on the load drawn by the lamp. The programming which determines a condition of the lamp based on the load drawn by the lamp and includes processing steps which read the load shortly after the lamp is turned on then again after predetermined time, calculate the load difference, and determine whether the load difference exceeds a predetermined threshold to detect a failed lamp condition. The programming which determines a condition of the lamp based on the load drawn by the lamp may also or alternatively include processing steps which calculate whether the load difference at predetermined times exceeds a predetermined threshold, and counts the number of times the load difference exceeds the predetermined threshold to detect a cycling lamp condition.
The programming which determines a condition of the photocontroller based on the load drawn by lamp includes processing steps which determine whether current is drawn by the lamp during daylight hours to detect a relay fault condition. The programming which determines a condition of the photocontroller based on the load drawn by lamp may also or alternatively include processing steps which determine whether the lamp is on or off for a period of time greater than a preset threshold to detect a photocell fault condition.
This invention also features a method of diagnosing the operability of photocontroller components such as the relay and/or the photocell sensor. The method includes detecting whether a load is drawn by a lamp; determining whether it is daylight; determining whether the load is continuously drawn by the lamp for a period of time greater than a preset threshold; and sending a fault signal if a load is drawn by the lamp during daylight or if a load is drawn by the lamp for a period of time greater than the preset threshold. The method of this invention also includes diagnosing whether the lamp is properly operating. The method includes reading the load shortly after the lamp is turned on then again after predetermined time, calculating the load difference, and determining whether the load difference exceeds a predetermined threshold to detect a failed lamp condition. In addition, a cycling lamp condition may be detected by calculating whether the load difference at predetermined times exceeds a predetermined threshold, and counting the number of times the load difference exceeds the predetermined threshold to detect a cycling lamp condition.